The present invention generally relates to piezoelectric vibrators and more particularly, to a wafer of piezoelectric vibrators which is especially adapted for use in a novel method of manufacturing piezoelectric vibrators through employment of such a wafer of piezoelectric vibrators.
Conventionally, as a piezoelectric vibrator or resonator, there has been provided a vibrator which utilizes an expansion mode vibration of long sides or short sides of a piezoelectric vibrating portion formed into a rectangular shape. For one example of such a vibrator, there is shown in FIG. 1, a piezoelectric vibrator chip 1 employing the expansion mode vibration in the direction of its short sides, with the outer casing thereof omitted for brevity.
The above piezoelectric vibrator chip 1 includes a vibrator portion 2 constituted by a metallic material having a constant modulus of elasticity such as Elinvar or the like, a piezoelectric thin film 3 of ZnO, etc. formed on one surface of the vibrator portion 2 by sputtering, a vibrating electrode film 4 further formed on the surface of said piezoelectric thin film 3 through vacuum deposition, and a frame portion 6 connected to central portions of the short sides of said vibrator portion 2 by a pair of connecting portions 5, with said vibrating portion 2, connecting portions 5 and frame portion 6 being integrally formed as one unit.
The piezoelectric thin film 3 is further extended from the connecting portion 5 at one side towards one corner portion of the frame portion 6 as an extended piezoelectric thin film 3b, while on the surface of said extended piezoelectric thin film 3b, the vibrating electrode film 4 is similarly extended as an extended electrode film 4b. This extended electrode film 4b functions as a lead-out electrode, and thus, the extended piezoelectric thin film 3b has a function to electrically insulate the lead-out electrode 4b from the frame portion 6.
In the piezoelectric vibrator chip 1 having the construction as described so far, an external lead-out line 9 is connected to the lead-out electrode 4b, while another external lead-out line 10 is connected to the other corner portion of the frame portion 6.
As a vibrator in which the vibrator portion, frame portion and connecting portions for the connection therebetween are integrally formed by a metallic material as described above, there is also available an arrangement which employs, for example, a flexural mode vibration.
In the piezoelectric vibrators having the configuration as described so far, the vibrator chips thereof are not produced one piece by one piece, but are produced in one integral unit in which frames of a plurality of vibrator chips are connected to each other through more than one joint (such an integral unit is referred to as a piezoelectric vibrator wafer hereinafter), is prepared and the joints are removed after the wafer has been passed through predetermined processes to obtain individual vibrator chips. For removal of the joints, there may be used a scribing process employing a rotary blade, or another scribing process using laser. These processes, however, require an expensive facility and high accuracy for the positioning of workpieces at the cutting position, while moreover, it has been necessary to fix the piezoelectric vibrator wafer during cutting, thus presenting a bottleneck in continuous mass production. Furthermore, there are many problems to be solved such as removal of a fixing agent remaining adhered to the piezoelectric vibrator wafer, countermeasures against scattering of swarf during the cutting, removal of burrs, supplying of cooling or lubricating agents, etc., and these problems tend to be more difficult to solve as the objects to be dealt with become small in size.